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Can you do too much exercise?

Legend has it that Philippides, a Greek messenger, ran 25 miles from Marathon to Athens circa 490 BC, delivered his message and promptly died. Did he die from too much exercise?

More likely he died from not enough exercise . He wasn’t properly trained to run that distance. Fast forward to 1896 when modern marathon races began. Since then, millions upon millions have safely trained and completed marathons.

The question of whether someone can exercise too much has been around for decades. The debate intensified following the death of legendary runner/author James Fixx while running at the age of 52 in 1984. As a result, many people questioned the wisdom of exercising.

But Mr. Fix had heart disease in his family. His father died of a heart attack when he was 43. And an autopsy of Mr. Fix revealed blockages in his heart arteries. But since he was running alone when he died, no one knows exactly what happened. Did he experience symptoms while running? Did he try to seek help?

Can too much exercise give you heart disease?

However, every so often a study comes out stating too much exercise may be bad for your heart. This study found that white men who exercised three times more than the physical activity guidelines (150 minutes of moderate activity per week), had greater coronary artery calcification (CAC- an indicator of blockage in the heart arteries), compared to white men not meeting the physical activity guidelines.

What’s remarkable about this finding is the levels of exercise that were associated with problems for the heart were quite low- only about an hour a day. This isn’t much at all and an amount that many people are already doing.

So is this study conclusive that you can do too much exercise? No.

First off this study used CAC as an indicator of heart disease. While CAC is a marker of heart disease, it doesn’t mean someone with a high amount of CAC will have a heart attack.

Secondly, the association between exercise and higher CAC was only present in white men, but not in the white women, black men and black women also in the study. Which the authors acknowledged could be a chance finding.

Lastly, and perhaps most important, is that other studies have shown atherosclerosis in athletes tend to be more stable. Being more stable, means the person is less likely to have a heart attack compared to inactive people with atherosclerosis. So it is possible the CAC seen in athletes is actually protective.

In addition, numerous other studies have shown higher levels of exercise to be protective. We reported benefits of activity at levels 17 times that of the guidelines (effectively walking for eight hours per day). This has been confirmed in a subsequent research.

Are you at greater risk when exercising?

Yes, when being active, there is a greater chance of dying or having heart problems compared to doing nothing. This risk though is extremely small.In women, it’s about 1 sudden cardiac death in 36.5 million hours of exercise. Compare this to 1 death in 59.4 million hours of doing nothing like sitting.

Similar findings have also been found in men and indicate that regular exercise actually lowers the risk. To put this into perspective, a person living to 75 years lives for 657 000 hours. So the risk is very small and it gets smaller as a person gets in better shape from exercising.

There are situations in which too much exercise could be a problem. Following an ultramarathon (a 160 km run), runners experience changes in their heart function that may reflect damage to the heart. However, it’s not clear if these changes are a problem or not. It is possible these changes are favourable adaptations to exercise. And we do now that people exercising consistently outlive people who don’t.

The overwhelming evidence suggests that regular activity and exercise is good for us. It prevents heart and other diseases, as well as increasing lifespan. While there may be adverse effects in people who do extremely high amounts of strenuous exercise, the findings are unclear.

For many of us, though, we are going to do nowhere near that amount of exercise. We should take pause and recognize the main problem in our society is that people don’t do enough exercise, not that they do too much.

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